Miniature pin terminal connector



Sept? 1969 J. H. KREHBIEL 3,465,279

MINIATURE PIN TERMINAL CONNECTOR Filed Sept. 8, 1967 United States Patent 3,465,279 MINIATURE PIN TERMINAL CONNECTOR John H. Krehbiel, Downers Grove, Ill., assignor to Molex Products Company, Downers Grove, III., a corporation of Illinois Filed Sept. 8, 1967, Ser. No. 666,299 Int. Cl. H01r 13/20, 13/50, 9/08 US. Cl. 339-30 .Claims ABSTRACT OF THE DISCLOSURE Miniature pin terminal connectors comprising complementary male and female terminals formed of stamped and rolled sheet metal having flanges for crimped, solderless connection to a wire, and having struck out protuberances for positioning and retaining the terminals in insulated housings.

With increasing complexity of electrical devices, and with continuing pressure for miniaturization thereof, it has become necessary to provide separable connectors having a large number of contacts or terminals therein. Terminals of this type which are quite satisfactory down to a very small size are disclosed and claimed in my prior Patent No. 3,178,673 for Wire Connector.

However, .as terminals for separable connectors have become even smaller in size, the electrical current densities have necessarily gone up. Increasing current densities increase the operating temperatures of the connectors, and this has been found to cause the female connector to relax to some extent with little or no corresponding increase in size of the male connector, thus rendering the connection looser, introducing more resistance, and further increasing the current density, with an increase in temperature, in a snowballing effect.

The present invention comprises longitudinally slit, tubular terminals of male and female shape, wherein the male terminal has a greater coefiicient of thermal expansion than the female. Each terminal has resilient stop means which engage a shoulder adjacent one end of a bore of a respective mating insulating connector body, with an enlarged terminal portion engaging an interior wall portion of the bore. A second shoulder is formed adjacent the opposite end of each bore and corners of each terminal at the slit are deflected outwardly to present tapered surfaces which engage the second shoulder.

Accordingly, it is an object of this invention to provide a superior pin terminal connector that maintains a tight fit with temperatures within a normal operating range, irrespective of resistance heating elfects.

It is further an object of the present invention to provide struck out protuberances commensurate with the size of the terminals for properly mounting the terminals in insulated housings.

It is further an object of the present invention to provide male and female complementary terminals in which the pressure of engagement between them increases or intensifies upon heating thereof by electric current passing therethrough.

It is further an object of the present invention to provide structure in miniature pin terminals for gripping wire in such manner as to cut through oxidation or enamel thereon to make good electric contact with the wire.

Other and further objects and advantages of the present invention will be apparent from the following description when taken in connection with the accompanying drawings wherein:

--FIG. 1 is a plan view on a slightly enlarged scale of a series of miniature male terminals in accordance with ice the present invention as delivered by a stamping and forming machine;

FIG. 2 is an enlarged plan view of one of the male terminals of FIG. 1;

FIG. 3 is a fragmentary side view on an intermediate enlarged scale of the terminal of FIG. 2 as taken substantially along the line 3--3 in FIG. 2;

FIG. 4 is an end view thereof as taken along the line 4-4 in FIG. 2;

FIG. 5 is a cross sectional view as taken substantially along the line 5-5 in FIG. 2;

FIG. 6 is a view similar to FIG. 2 but showing a female terminal;

FIG. 7 is a longitudinal sectional view through the terminal of FIG. 6 substantially along the line 77 in FIG. 6;

FIG. 8 is a fragmentary detail view of a portion of the terminal of FIG. 7 as taken along the line 8-8 in FIG. 7;

FIG. 9 is a longitudinal cross sectional view of a mating male and female terminal mounted within their respective housings;

FIG. 10 is a longitudinal sectional view on an enlarged scale as taken substantially along the line 10'10 in FIG. 2 and showing a detail thereof; and

FIG. 11 is a perspective view showing a separated plug and receptacle construction incorporating the terminals of the present invention.

Turning now to the drawings in greater detail, and first to FIG. 1, there will be seen a plurality of male terminals 20 disposed in parallel array between a pair of bands or ribbons 22 of sheet metal, the terminals and bands having been formed integrally from a blank strip of suitable resilient metal, such as brass or steel, and the terminals being attached to the side bands or ribbons 22 by means of readily severable sections 24.

Each of the male terminals 20, as seen in detail in FIGS. 25, includes a cylindical shank 26 with a conical entering end, tip, or nose 28 thereon. A longitudinal gap 30 extends through the cylindrical body, closing at the nose as indicated at 32, and continuing through the nose to the extreme end thereof as a closed seam 34. In the side and end views of FIGS. 3 and 4, it will be seen that there are also two symmetrically disposed side seams 36 in the nose to facilitate formation of the nose from the initially flat blank, and to insure a tight entering end of minimum dimension, yet with dimension stability, with no projections or openings for snags, and with maximum metal in the tip.

At the rear end of the shank 26 opposite the nose 28 there is a line of demarcation 38 at which point the diameter of the shank increases slightly. In addition, two resilient wings 40 flare outwardly and rearwardly diametrically opposite one another and from the sides of the terminal. Rearwardly of the extremities of the wings 40 the diameter of the male terminal further expands in a taper 42 to a body portion 44 that further expands or tapers outwardly as it moves rearwardly of the terminal. As will be seen in FIG. 5, the body portion 44 is approximately cylindrical in shape, although the sides thereof may flare somewhat outwardly and form an obtuse angle portion 46 in cross section. The sides and top of the rear portion of the body are cut away as at 48, leaving the upper portions of the body as free flanges 50. The corners of these flanges are struck up and out at 52, thereby providing stops limiting the entering movement of the terminal in a housing. At this point it will be enlightening to refer to FIG. 7 which is a side view of the female terminal. However, the parts now under discussion are substantially identical, and are identified by similar numerals with the addition of the sufiix a.

In any event, the upwardly and outwardly turned tips 52a are readily visible in FIG. 7.

Starting just short of the rear edges of the flange 50, there is a hole 54 of more or less rectangular nature along the bottom center line of the terminal. As will be seen in connection with the female terminal in FIGS. 7 and 8, the hold 54a therein is formed by a pair of downwardly stamped flanges 56a symmetric about an axial plane. The upper edges 58a of these flanges are on a common plane with the struck our corners 52a, such plane being perpendicular to the axis of the terminal, and these edges act with the corners as in-stops limiting the inserting movement of the terminal in a housing. Also in FIGS. 7 and 8, it will be seen that there is a longitudinal rib 60 extending out from the body 44a and having a forward edge 62a substantially on a line with the outward flare 42, 42a of the rear end terminating at the hole or aperture 54, 54a. It will be understood that the rib construction is the same for either the male or female terminal.

Rearwardly of the flanges 56, 56a, the terminal includes a wire gripping section 64 having a pair of upwardly and outwardly projecting flanges 66 in more or less U relation. These flanges are designed to be crimped against a wire, generally in the same manner as described in my previous Patent 3,178,673, and as may be seen near the top portion of FIG. 9. Immediately rearwardly of the wire gripping section 64, and spaced therefrom by notches 68, is an insulation gripping section 70, likewise comprising a pair of flanges 72 in U-shaped relation, the flanges 72 being somewhat larger than the flanges 70, whereby to grip the insulation 73 on the wire, as may be seen closer to the top of FIG. 9. As will be apparent, such gripping of the insulation keeps it from working back away from the terminal to expose bare wire, such as might happen through vibration, or through an indiscreet pull on the wire insulation.

Reference heretofore has been made to the female terminal shown in P68. 6, 7, and 8, and this terminal is hereinafter identified by the numeral a, due to the general similarity to the male terminal 20. As has been adverted to, similar parts are identified throughout by the addition of similar numerals with the suflix a. There is a shank 26a which is hollow, and of nearly cylindrical cross section, like the shank 26, a significant difference being that this shank tapers in very slightly in diameter from the outer or rear portion adjacent the wings 40a toward the open end or tip, which flares outwardly at 28a. The center gap 30a likewise tapers, being somewhat narrower at and adjacent the outward flare 28a than at the rear end. The significance to the taper is that the internal diameter of the shank 26a adjacent the flare 28a is slightly less than the outside dimeter of the male shank 26. Consequently, when the male shank is inserted in the female shank, the female shank is distended into cylindricity in surface engagement with the male shank 26. This has an initial advantage in providing a large surface area of contact for current flow with little resistance heating, particularly as opposed to a line or point contact as is not uncommon in the prior art. Furthermore, since the female shank initially is somewhat overformed, any relaxation thereof upon heating upon carrying of current will simply lessen the surface pressure on the male shank slightly, without withdrawing the female shank from the male shank in any way, which unfortunate happening in the prior art has led to a poorer contact and further heating, etc.

In accordance with one preferred example of the present invention, the male and female terminals are made of metals of somewhat different rates of thermal expansion. The male member expands relatively more rapidly than the female member, and the female member material may actually have a negative coefiicient of thermal expansion.

A preferred feature of the invention is shown in FIG.

10. As shown therein, the wire gripping section 64 intermediate the side gripping flanges 66 is provided with transverse slots or grooves 74. These slots or grooves are not simply stamped in the sheet metal, but are actually coined therein. Accordingly, the corners 77 of each groove are quite sharp. Thus, when the wire 76 is laid in the wire gripping section, and the flanges 66 are crimped down on top of the wire, some of the metal of the wire is extruded into the grooves as indicated at 78. The coined, sharp corners 77 actually bite into the metal of the wire 76 bearing in mind that the wire is copper, while the terminal metal is brass steel, and thereby insure a good contact between the terminal and the wire, even though the wire may be somewhat oxidized or otherwise corroded. In fact, the terminal as now described, can be applied directly to enameled motor wire without scraping off the enamel. As will be apparent, the metal 78 is stretched in passing into the grooves 74, whereby some of the enamel is sheared off. Specifically, the enamel breaks at the corner 77 of the terminal metal, and is drawn down into the grooves, whereby there is a good contact between the terminal metal and the extruded wire portions 78 along the sides of the grooves, as indicated at 80.

In a typical example of the invention, the wire is #30 wire .009 inch in diameter. The terminal metal is .008" thick, while the coined grooves are about half that, being about .0O3-.'004" deep. These grooves are about .010" wide and are spaced about .014"-.015" on centers.

A plurality of male terminals is installed in a molded plastic plug 82 seen in FIGS. 9 and 11. This plug has a socket 84, of preferably rectangular shape, formed by a circumferential wall 85, and has a pair of oppositely disposed openings 86 therein. A receptacle 88, also of molded plastic, receives a plurality of the female terminals 20a and is received in the socket 84, being releasably held therein by cam-like detents 90 respectively fitting in the apertures or openings 86.

With specific reference to FIG. 9, the plug 82 is provided with a plurality of bores 92 each receiving a terminal 20 therein. The bores 92 open into the socket 84, with the shanks 26 extending into the socket and with the rearwardly and outwardly directed flanges 40 abutting the bottom wall or shoulder 94 of the socket to prevent unauthorized withdrawal of the terminals. The bores 92 each are provided part of the way in, and short of, the bottom wall 94, with shoulders 95 against which the outwardly deflected tips 52 and the edges of the downwardly struck flanges 56 impinge to limit inward movement of the terminals. The terminal is centered in the bore 92 by the flanges 50 and rib 60 which abut the bore wall.

The positioning of the female terminals in the receptacle 88 is generally similar, and the use of the suflix a avoids the necessity of repetition of discussion. However, it will be apparent that some distance in from the entering face 96 of the receptacle the bores 9211 are constricted in diameter to provide shoulders 98 against which the flanges 40a abut. The flared tips 98a of the female terminals are slightly recessed, as will be apparent. As will be seen in FIG. 9, the insertion of the receptacle 88 in the socket 84 of the plug 82 causes the male shanks 26 to telescope with the female shanks 26a in surface engagement, the female shanks being slightly distended during this operation, as previously noted.

It will now be apparent that I have invented a superior miniature pin terminal of rather small size, for example the male shank 26 being no more than in diameter and the overall length of the male terminal from the entering tip 34 to the rear end of the insulation gripping flanges 72 being slightly over /3". Surface contact between the male and female members, even upon heating attendant upon the carrying of current, is maintained through superior design, and through proper use of materials. The stops limiting insertion of the terminals in plastic housings, and the flanges preventing withdrawal thereof, are of a minimum size commensurate with the size of the terminals, while the coining of grooves in the wire gripping section insures excellent electrical contact of a terminal with a wire, irrespective of oxidation of the Wire, or even of enamel insulation on a wire.

The particular example of the invention as herein shown and described is for illustrative purposes only. Various changes in structure will no doubt occur to those skilled in the art.

The invention is claimed as follows:

1. An electrical connector comprising an insulating body having a bore therethrough which includes oppositely outwardly facing shoulders contiguous to said bore and relatively adjacent the opposite ends thereof, and a resilient metallic terminal member positioned in said bore, said member comprising a substantially tubular body having a longitudinal slot extending from end to end thereof, said tubular body having resilient stop means snapped over and engaging one of said shoulder to resist unauthorized withdrawal of the terminal member, and an enlarged section rearwardly of said stop means including a portion thereof in engagement with the bore between said oppositely facing shoulders, said enlarged section including at the end thereof remote from said resilient stop means rear edges which cooperate with said slot to define tinelike corners, said corners being deflected outwardly to present a tapered surface which engages the other of said shoulders to limit inward movement of said terminal member.

2. An electrical connector as defined in claim 1, further including flange means struck out of said tubular body and positioned to engage the same shoulder as said deflected corners.

3. An electrical connector as defined in claim 2, wherein said flange means comprise a pair of flanges struck out of said tubular body and symmetrically disposed with regard to an axial plane.

4. An electrical connector as defined in claim 1 wherein said tubular body further includes a portion rearwardly of said enlarged section which is adapted to be crimped about a wire lead into gripping engagement therewith, said portion having depressions coined therein which present sharp corners for biting into the metal of said Wire leads upon crimping of said portion thereto.

5. An electrical connector comprising a pair of similar insulating bodies each having a bore therethrough, each said bore including oppositely outwardly facing shoulders contiguous thereto and relatively adjacent the opposite ends thereof, and a pair of metallic terminal members positioned in said bore one of which being a male terminal and the other being a female terminal in which said male terminal is received, each said terminal member comprising a substantially tubular body having a longitudinal slot extending from end to end thereof, said tubular body having resilient stop means snapped over and engaging one of said shoulders to resist unanthorized withdrawal of the terminal member from its respective insulating body, and an enlarged section rearwardly of said stop means including a portion in engagement with the bore between said oppositely facing shoulders, said enlarged section including at the end thereof remote from said stop means rear edges which cooperate with said slot to define tinelike corners, said corners being deflected outwardly to present tapered surfaces which engage the other of said shoulders to limit inward movement of the terminal member, and said male terminal member having a greater coeflicient of thermal expansion than said female terminal member whereby firm engagement be tween said terminals is maintained irrespective of the heating thereof.

References Cited UNITED STATES PATENTS 1,635,831 7/1927 Gagnon 339-30 2,677,116 4/1954 Ritter 339-193 3,072,880 1/1963 Olsson 339-221 X 3,083,351 3/1963 Nielsen 339-217 3,097,906 7/1963 Shannon 339-256 X 3,178,673 4/1965 Krehbiel 339-217 3,196,380 7/1965 Krehbiel 339-217 X 3,209,091 9/1965 Freathy et a1. 200-51 3,311,866 3/1967 Williamson 339-217 RICHARD E. MOORE, Primary Examiner US. Cl. X.R. 339-176, 211, 217 

